Position estimation device, position estimation method, and storage medium

Abstract

A position estimation device ( 10 ) includes an image acquisition unit ( 110 ) and a position estimation unit ( 120 ). The image acquisition unit ( 110 ) acquires a plurality of images generated by an imaging device that images a target space that is a space in which a flying object flies. The position estimation unit ( 120 ) estimates a position of the flying object by processing the plurality of images. The position estimation unit ( 120 ) provisionally sets a type of the flying object and estimates a distance to the flying object and a speed. Then, the position estimation unit ( 120 ) updates the type of the flying object by using the speed and a change rate in an area of the flying object in the image. The position estimation unit ( 120 ) repeats the processing.

1 . A position estimation device comprising:
 at least one memory configured to store instructions; and   at least one processor configured to execute the instructions to:   acquires a plurality of images generated by an imaging device that images a target space that is a space in which a flying object flies; and   estimates a position of the flying object by processing the plurality of images,   wherein estimating the position of the flying object includes   (1) provisionally setting a type of the flying object,   (2) specifying three or more of the images arranged in time series as a target image group,   (3) estimating a distance from the imaging device to the flying object for each of a plurality of the images included in the target image group by using the provisionally set type and an area of the flying object in the image belonging to the target image group,   (4) calculating a change rate in the area of the flying object between the plurality of the images included in the target image group,   (5) estimating a speed of the flying object by using the distance to the flying object and a position in the image in each of the plurality of the images included in the target image group,   (6) updating the type of the flying object by using the speed and the change rate in the area, and   (7) performing processing shown in (2) to (6) again by using the type updated in (6) until a predetermined criterion is satisfied, and   an estimated position of the flying object at a timing at which the image is captured is indicated by a position of the flying object in the image and the distance calculated based on the image.   
     
     
         2 . The position estimation device according to  claim 1 ,
 wherein the distance in (3) is estimated with using a focal length when the imaging device generates the image.   
     
     
         3 . The position estimation device according to  claim 1 ,
 wherein estimating the position of the flying object, in (3), includes calculating an average value of the areas between the image and at least one other image belonging to the target image group, and estimates the distance using the average value.   
     
     
         4 . The position estimation device according to  claim 3 ,
 wherein estimating the position of the flying object includes, in (3), further estimating motion information that is at least one of a turning radius, an angular velocity, an acceleration, or an angular acceleration of the flying object, and   estimating a future position of the flying object by using the position, the speed, and the motion information of the flying object.   
     
     
         5 . The position estimation device according to  claim 4 ,
 wherein estimating the position of the flying object includes, after performing processing shown in (1) to (6) at least once, updating the target image group in (2) each time when the new image is acquired, performing (3) on the target image group after the update,   between (5) and (6),   calculating a moving average of each of the position, the speed, and the motion information of the flying object by using the position, the speed, and the motion information of the flying object repeatedly calculated in ( 3 ), and   estimating the future position by using the moving average.   
     
     
         6 . The position estimation device according to  claim 4 ,
 wherein the predetermined criterion is that a difference between the estimated position at a first timing and the future position at the first timing generated before the first timing is equal to or less than a criterion value.   
     
     
         7 . The position estimation device according to  claim 1 ,
 wherein the target space is imaged by a plurality of the imaging devices from different directions,   acquiring the plurality of images includes the plurality of images from each of the plurality of imaging devices, and   estimating the position of the flying object includes calculating information indicating the position of the flying object for each of the plurality of imaging devices and estimates the position of the flying object by using the information.   
     
     
         8 . The position estimation device according to  claim 1 ,
 wherein the imaging device is a monocular camera.   
     
     
         9 . The position estimation device according to  claim 1 ,
 wherein the predetermined criterion is selectable.   
     
     
         10 . A position estimation method comprising:
 performing, via a computer,   acquiring a plurality of images generated by an imaging device that images a target space that is a space in which a flying object flies, and   estimating a position of the flying object by processing the plurality of images,   wherein in estimating the position of the flying object includes   (1) provisionally setting a type of the flying object,   (2) specifying three or more of the images arranged in time series as a target image group,   (3) estimating a distance from the imaging device to the flying object for each of a plurality of the images included in the target image group by using the provisionally set type and an area of the flying object in the image belonging to the target image group,   (4) calculating a change rate in the area of the flying object between the plurality of the images included in the target image group,   (5) estimating a speed of the flying object by using the distance to the flying object and a position in the image in each of the plurality of the images included in the target image group,   (6) updating the type of the flying object by using the speed and the change rate in the area, and   (7) performing processing shown in (2) to (6) again by using the type updated in (6) until a predetermined criterion is satisfied, and   an estimated position of the flying object at a timing at which the image is captured is indicated by a position of the flying object in the image and the distance calculated based on the image.   
     
     
         11 . A non-transitory computer readable storage medium storing a program causing a computer to execute:
 acquiring a plurality of images generated by an imaging device that images a target space that is a space in which a flying object flies; and   estimating a position of the flying object by processing the plurality of images,   wherein estimating the position of the flying object includes   (1) provisionally setting a type of the flying object,   (2) specifying three or more of the images arranged in time series as a target image group,   (3) estimating a distance from the imaging device to the flying object for each of a plurality of the images included in the target image group by using the provisionally set type and an area of the flying object in the image belonging to the target image group,   (4) calculating a change rate in the area of the flying object between the plurality of the images included in the target image group,   (5) estimating a speed of the flying object by using the distance to the flying object and a position in the image in each of the plurality of the images included in the target image group,   (6) updating the type of the flying object by using the speed and the change rate in the area, and   (7) performing processing shown in (2) to (6) again by using the type updated in (6) until a predetermined criterion is satisfied, and   an estimated position of the flying object at a timing at which the image is captured is indicated by a position of the flying object in the image and the distance calculated based on the image.